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A128851
Denominators of the continued fraction convergents of the decimal concatenation of the prime-indexed primes.
1
1, 2, 3, 17, 20, 37, 94, 131, 225, 581, 806, 1387, 2193, 3580, 63053, 66633, 129686, 196319, 522324, 718643, 2678253, 8753402, 20185057, 69308573, 436036495, 941381563, 9849852125, 10791233688, 20641085813, 31432319501, 83505724815
OFFSET
0,2
COMMENTS
Prime-indexed primes (pips) or primeth primes 3, 5, 11, 17, 31, 41, 59, 67, ... are concatenated and then preceded by a decimal point to create the fraction N = .35111731415967... This number is then evaluated with n=0, m=steps to iterate, x = N, a(0)=floor(N) using the loop: do a(n)=floor(x) x=1/(x-a(n)) n=n+1 loop until n=m.
PROG
(PARI) cattpips(n) = { a="."; forprime(x=2, n, a=concat(a, prime(x))); a=eval(a) }
cfrac2(m, f) = { default(realprecision, 1000); cf = vector(m+10); cf = contfrac(f); for(m1=1, m-1, r=cf[m1+1]; forstep(n=m1, 1, -1, r = 1/r; r+=cf[n]; ); numer=numerator(r); denom=denominator(r); print1(denom", "); ) }
CROSSREFS
Cf. A128850 (numerators).
Sequence in context: A121409 A041295 A128845 * A078737 A041981 A197223
KEYWORD
frac,nonn,base
AUTHOR
Cino Hilliard, Apr 16 2007
EXTENSIONS
Edited by Charles R Greathouse IV, Apr 25 2010
STATUS
approved